1. Field of the Invention
The invention relates to an electronic device, and more particularly, to a swivel hinge assembly for an electronic device, such as a portable electronic device.
2. Background of the Related Art
FIGS. 1A to 1C show a related art portable electronic device having a swivel hinge. Referring to FIGS. 1A to 1C, a variety of parts, such as a main board and a hard disk drive, are installed within a main body 1. A keyboard 3 which functions as an input device is provided on a top surface of the main body 1. A display unit 5 is connected to an end of the main body 1. Generally, a liquid crystal display (LCD) is used as the display unit 5; however, other types of display units may also be appropriate.
The display unit 5 can be pivoted to be folded or unfolded with respect to the main body 1, as shown in FIGS. 1B and 1C, and can also be rotated horizontally as viewed from the front of the main body 1, as shown in FIG. 1C. This is possible because the main body 1 and the display unit 5 are connected to each other by a swivel hinge assembly 7.
The swivel hinge assembly 7 allows the display unit 5 to be rotated horizontally about a rotary plate 7r. An end of a connection plate 7c is connected to the rotary plate 7r. A center of rotation in a fore and aft direction is positioned along a tangential direction of a circular arc defined by and at the periphery of the rotary plate 7r. Thus, the central axis of rotation in the lateral direction and the central axis of rotation in the fore and aft direction are not orthogonal to each other on the same plane.
In such a related art, the display unit 5 is pivoted in a fore and aft direction on the top surface of the main body 1, that is, pivoted about the horizontally extending axis of rotation on the one end of the connection plate 7c, to be folded or unfolded with respect to the main body 1. At the same time, the display unit 5 is rotated horizontally about a vertically extending axis of rotation provided on the rotary plate 7r. 
Therefore, the display unit 5 can be used in various rotated states. More particularly, the display unit 5 can be used in a state in which a rear surface thereof is in close contact with the top surface of the main body 1, as shown in FIG. 1C. Thus, the display unit 5 may be used as a tablet computer.
However, there are the following problems in the related art.
Since the rotary plate 7r of the swivel hinge assembly 7 is in the shape of a circle, the swivel assembly 7 occupies a large area on the top surface of the main body 1. Therefore, the keyboard 3 cannot be installed in at least a portion having a width corresponding to a diameter of the rotary plate 7r. In other words, right and left areas on the top surface of the main body 1 with respect to the rotary plate 7r are not available for placement of the keyboard 3.
Further, there is the inconvenience in the related art that the keyboard 3 is located near the front end of the main body 1 and thus there are no portions for supporting the wrists of a user when the user presses the keys of the keyboard 3. To solve the aforementioned problems, the swivel hinge assembly 7 must be formed to protrude from the rear end of the main body 1. However, if the swivel hinge assembly 7 protrudes from the rear end of the main body 1, an external appearance of the device is not suitable for design purposes. Further, the display unit 5 is unstable since the display unit 5 may be positioned beyond the rear end of the main body 1.